1 Answer
1

I'd recommend the biggest one you can fit. Generally speaking, more metal in the air makes for better receiving. Having an antenna tuned for the frequency you're listening to is of a slight advantage, often more than offset by having a bigger antenna. 2 and a half feet would probably be about optimal for auto usage. That's 1/4 wavelength in (roughly) the middle of the FM band. A 6" antenna is going to be less than 1/16 wavelength and not tuned at all. Might suit your purposes if you only like strong/nearby stations, but definitely won't be ideal.